Improvement in taps



L. D. CASTLE &'J. W. STRONG.

Tap.

Patened May 13,1879.

' INVENT'OR: QM BY 7 ATTORNEYS.

' WITNESSES 64% f g w /mo/w UNITED STATES PATENT OFFICE.

LEWIS 1). CASTLE AND JOHN W. STRONG, OF BRIDGEPORT, CONNECTICUT.

IM PROVEMENT IN TAPS.

Specification forming part of Letters Patent No. 215,264, dated May 13,1879; application filed August 31, 1878.

To all whom it may concern:

Be it known that we, LEWIS D. CASTLE and JOHN W. STRONG, of Bridgeport,in the county of Fairlield and State of Connecticut, have invented a newand Improved Tap, of which the following is a specification.

The object of this invention is to provide a tap that can be constructedmore cheaply and will last longer than those now in use.

The invention will first be described in connection with the drawings,and then pointed out in the claim.

In the accompanying drawings, Figure 1 represents a side elevation of myimprovement. Fig. 2 is a longitudinal section of the same on line as w,-and Fig. 3 is a transverse section thereof on line 3/ y.

Similar letters of reference indicate correspondin g parts.

A represents the body of the tap, and c is the shank thereof, to which awrench is applied in operating the tap. The surface of A tapers towardthe lower end, and its surface, about a third of the distance from theupper end, is formed with a screw-thread, as shown at l).

a at a a are longitudinal grooves in the surface of the body A,equidistant from each other. The bottom of the groove a has the sametaper as the surface of body A.

B are the cutters, which are made separately, of fin ly-tempered steel,and of a size to fit and slide freely in the grooves a. These cutters Bhave cutting-threads similar to an ordinary tap, which threads projectabove the surface of body A when the cutters are in place. The cutters Bare held in place in the groove a by an internally-threaded,ring, c,

which engages the threads of the cutters B and the thread I) on the bodyof the tap, as

seen in Figs. 1 and 2. The cutters are thereby also permits the removalof a broken cutter and insertion of a new one.

In placing the cutters in their grooves a, the thread 1) becomes a guidefor setting them so that the cutters will follow in the proper lead;and, if desired, the end of the cutters that projects when they are setdown maybe ground off.

We are aware that it is not new to provide a tap-stock with longitudinalgrooves to receive a similar grooved frame that receives cutter held bya threaded ring 5 but the latter has a shoulder on the inside at one endthat comes in cont-act with a shoulder on stock. This cannot be done inthe smaller sizes, and necessitates the cutting away ofso much of thestock as to weaken and render it liable to twist.

What we claim is-- A tap consisting of the grooved tapered body A,threaded at b, the cutters B, arranged in grooves a, and the threadedring C, all constructed substantially as shown and described.

LEWIS D. CASTLE. JOHN W. STRONG.

Witnesses:

JOHN B. RoLLINs, A. B. CHASE.

